I have the answer already I just need my worked checked so steps are not needed!!
1 answer:
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Answer:
For first part, t= 0.18 sec or 3.4 sec.
For second part, t= 3.7 sec.
Step by step answer:
First part:
Set h(t) = 17and solve for tt.
-16t²+ 58t + 7= 17
-16t² + 58t - 10 = 0
Solve this quadratic equation for t. You should get 2 positive solutions. The lower value is the time to reach 17 on the way up, and the higher value is the time to reach 17 again, on the way down.
Second part:
Set h(t) = 0 and solve the resulting quadratic equation for t. You should get a negative solution (which you can discard), and a positive solution. The latter is your answer.
cos (A - B) is 36/85
<h3>How to simply the identity</h3>
Expand cos(A - B) with the identity
You get, cos(A - B) = cos(A) cos(B) + sin(A) sin(B)
Since A is in quadrant II, so sin(A) > 0,
B is in quadrant I, so sin(B) > 0.
Using the Pythagorean identity, we get
cos²(A) + sin²(A) = 1
Make sin A the subject of formula
= (
)²)
Find the square root of both sides, square root cancels square
= 4/5
Repeat the same for the second value
= 15/17
Substitute values into cos(A - B)
cos(A - B) = cos(A) cos(B) + sin(A) sin(B) = (-3/5) * 8/17 + 4/5 * 15/17
cos (A - B) = 36/85
Therefore, cos (A - B) is 36/85
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